This invention relates generally to controlling the locking of doors, and more particularly the unlocking of doors as at their tops.
There is need for compact, simple, durable efficient and secure door unlocking systems, and methods, particularly when unlocking is needed at opposite sides of doors. This is of particular need when unlocking is required as in response to turning of door handles and no door latching mechanism is to be employed or is available, at vertical edges of doors, for security reasons.